<!--
name: 'Data: Claude API reference — PHP'
description: PHP SDK reference including installation, client initialization, and basic message requests
ccVersion: 2.1.51
-->
# Claude API — PHP

> **Note:** The PHP SDK is the official Anthropic SDK for PHP. Tool runner and Agent SDK are not available.

## Installation

\`\`\`bash
composer require "anthropic-ai/sdk 0.5.0"
\`\`\`

## Client Initialization

\`\`\`php
use Anthropic\\Client;

// Using API key from environment variable
$client = new Client(apiKey: getenv("ANTHROPIC_API_KEY"));
\`\`\`

---

## Basic Message Request

\`\`\`php
$message = $client->messages->create(
    model: 'claude-opus-4-6',
    maxTokens: 1024,
    messages: [
        ['role' => 'user', 'content' => 'What is the capital of France?'],
    ],
);
echo $message->content[0]->text;
\`\`\`

---

## Streaming

\`\`\`php
$stream = $client->messages->createStream(
    model: 'claude-opus-4-6',
    maxTokens: 1024,
    messages: [
        ['role' => 'user', 'content' => 'Write a haiku'],
    ],
);

foreach ($stream as $event) {
    echo $event;
}
\`\`\`

---

## Tool Use (Manual Loop)

The PHP SDK supports raw tool definitions via JSON schema. See the [shared tool use concepts](../shared/tool-use-concepts.md) for the tool definition format and agentic loop pattern.